Materials Literature
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A novel method is described for calculating the breakdown voltage of uniform field gaps in compressed air and SF/sub 6/ without the need for experiments. This method is based on the criterion of self-recurring single-electron avalanches developed in the gap. It is shown that the results computed by this method for pd…
Glassy B2O3 samples annealed at 300 °C at 10 and 15 kbar were densified by 9% and 11%, respectively. Relaxation by subsequent annealing at ambient pressure restored the original density. The structure of the pressurized samples was determined with x-ray diffraction. A new method was developed for eliminating the Compt…
Glasses containing up to 60-mol % PbF2 have been made in the binary system PbF2-B2O3. The glass transformation and crystallization temperatures, thermal expansion behavior, and electrical conductivity of these glasses have been measured. A corresponding series of lead borate glasses were also studied to provide a basi…
Garnets on the pyrope-grossular join have been synthesized, their unit-cell edges measured, and the activity of $$Ca_{3}Al_{2}Si_{3}O_{12}$$ component in $$Pyr_{85}Gr_{15}$$ determined experimentally at 1000°C. There is no significant departure from ideal volume mixing in the composition range 0 to 21 mole% $$Ca_{3}Al…
Hydrogenated amorphous carbon (HAC) films have been prepared by direct condensation of cool carbon vapor at low temperatures. Quantitative absorption coefficients for these films have been obtained between 0.16 and 20 microns. Spectra of HAC at 3.4 microns are quite similar to those seen in comet Halley and in the Gal…
The method of constant-stress molecular dynamics using the Parrinello-Rahman Lagrangian is described, particularly as applied to Coulomb systems. The method is used to simulate the phase behavior of silver iodide. The \ensuremath{\beta}, \ensuremath{\alpha}, rocksalt, and liquid phases are reproduced and the boundarie…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure, dynamic nuclear magnetic resonance study, and magnetic properties of the two novel chains [Cu(paphy)X](PF6).cntdot.H2O (paphy = pyridine-2-carboxaldehyde 2-pyridylhydrazone; X = Cl, Br). Synthetic strategy of one-dimensional systems of copper(II)Teofilo Rojo, Jose…
An analysis is given of the dual transformation and also the strip method which can yield the ideal octagonal quasilattice as well as its approximants. An ideal octagonal tiling consisting of 45° rhombi and squares can be derived from the projection of a 4D cubic lattice within an irrational 2D subspace onto an irrati…
Single-crystalline CdS films have been epitaxially grown on (100) and (111)A and B GaAs substrates at temperatures between 200 and 350°C by a low-pressure metalorganic chemical-vapor-deposition (MOCVD) method using (CH 3 ) 2 Cd and H 2 S gases. The (100)-oriented film exhibits perfectly cubic modification, but contain…
Several continuous SiC and SiC/N‐based ceramic fibers prepared from different polymer precursors have been characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and high‐resolution electron microscopy (HREM). Methods to prepare longitudinal as we…
The electronic structure of five antimony chalcogenides (${\mathrm{SbI}}_{3}$, ${\mathrm{Sb}}_{2}$${\mathrm{Te}}_{3}$, SbTeI, ${\mathrm{TlSbS}}_{2}$, and ${\mathrm{Tl}}_{3}$${\mathrm{SbS}}_{3}$) is investigated. Tight-binding band-structure calculations and molecular models are combined with x-ray diffraction and phot…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLow-temperature neutron powder diffraction study of chromium dioxide and the validity of the Jahn-Teller viewpointJeremy K. Burdett, Gordon J. Miller, James W. Richardson, and Joseph V. SmithCite this: J. Am. Chem. Soc. 1988, 110, 24, 8064–8071Publication Date (Print):Novemb…
Thermal and ion-induced reactions in codeposited, multilayer and bilayer Al-Ti and Al-Hf structures were studied by transmission electron microscopy and Rutherford backscattering. A metastable Al3 M (M being Ti or Hf) phase was found by both ion beam mixing and thermal annealing. The metastable phases have a cubic str…
Ferroelectric PbTiO(3) films 0.5- to 2.0-mum thick were prepared by the metalloorganic decomposition (MOD) process using multilayer spinning with firing temperatures of 490-630 degrees C. The temperature dependence of the dielectric constant was found to be a function of the c/a ratio, which could be modified by contr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLanthanide complexes of potentially heptadentate ligands including the structure of [tris(3-aza-4-methylhept-4-ene-6-on-1-yl)amine]tris(nitrato)gadolinium(III)Alexis Smith, Steven J. Rettig, and Chris OrvigCite this: Inorg. Chem. 1988, 27, 22, 3929–3934Publication Date (Prin…
The development and cellular differentiation of Dictyostelium discoideum are disrupted in transformants secreting high levels of the cyclic nucleotide phosphodiesterase. The aggregation of these cells in the early stage of development proceeds rapidly and without the formation of organized streams. The later stages of…
Thermodynamic equilibria were calculated to determine optimum fabrication conditions for SiC-whisker-reinforced Si{sub 3}N{sub 4} composite ceramics. Results of calculations indicate that pressureless sintering in a nitrogen atmosphere of 0.1 MPa may be performed at temperatures up to 2,123 K (1,850{degree}C) without…
Preserved diatom assemblages are found in deep water sediments in Lake Washington above and below an ash layer originating from an eruption of Mt. Mazama 6800 b . p . Total abundance of frustules did not change after the ash event, but a significant shift in community structure occurred. Melosira italica var. subarcti…
For pt.1 see ibid., vol.33, no.11, p.1239-48 (1988). Sonoluminescence, produced when a therapeutic ultrasound generator operating at 1 MHz was used to insonate a tank of water, was detected using a photomultiplier tube and analysed using pulse height analysis. Spectra of the number of counter per second were obtained…
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